1. Field of the Invention
The present invention relates to secure identification generally and, more particularly, but not by way of limitation, to unique identification method and means that employ a compound diffraction grating strip having first and second identification indicia encoded therein.
2. Background Art
Identification has become increasingly more important in a variety of settings. For example, employee identification cards may be used to gain access to security areas of a facility and/or in time and attendance reporting. Drivers"" licenses are often used to verify the identification of the possessors thereof. Various types of credit and debit cards are employed to make purchases, obtain cash or traveler""s checks, and/or to transfer funds, for example. In all of these settings, forgery and copying of such identification means result in the compromising of secret information and the loss of hundreds of millions of dollars worth of merchandise and cash annually. In many cases, credit card type identification is verified at the point of sale; however, as the need for more unattended credit card use expands, there is a greater need to verify the authenticity of the credit card to which the transaction is being charged.
One of the major methods used by forgers of credit cards is to obtain the numbers encoded on a valid credit card during a legitimate transaction and, at a later time, to include this number on another credit card. When the forged credit card is subsequently used on a transaction, the charge is applied to the valid number and the account of the owner of the valid credit card is charged accordingly. The only way to prevent this type of theft is to computer validate each transaction as the purchase is taking place and to have a cashier check the identification of the person purchasing the items against the name returned by the validation computer. While this procedure is economically justifiable when the purchase is for a relatively large amount and there is a cashier present, it is impossible to use this method for small transactions such as with vending machines, pay telephones, transit charges, automatic teller machines, and a host of other unattended charge applications.
There have also been elaborate attempts to create graphic patterns embellished with holographic photographic images to prevent forged credit cards from easily being produced. However, with today""s high-tech criminal element, credit cards and holographic images can be illegally produced and sold at high profits. In addition, this method of security still depends on the human element to inspect the card and identify the holder and to cancel the transaction, if necessary, something not appreciated by most physically exposed cashiers or clerks.
There have been a number of attempts to create secure identification means involving optical and/or magnetic information recorded on identification means. For example, in U.S. Pat. No. 5,627,663, issued May 6, 1997, to David J. Horan and James S. Bianco, and titled SECURE OPTICAL IDENTIFICATION METHOD AND MEANS, there is described a method of providing secure identification for an article, including: providing on the article a diffraction grating strip including a pattern of a series of diffraction grating elements, each the diffraction grating element to diffract light, from a light source, in one of at least three selected different planes; serially illuminating the diffraction grating elements, detecting changes in plane of diffracted light as the diffraction grating elements are serially illuminated, and generating first information representative of the changes in plane; storing the first information representative of the changes in plane; subsequently, serially illuminating the diffraction grating elements, detecting changes in plane of diffracted light as the diffraction grating elements are serially illuminated, and generating second information representative of the changes in plane; and then, comparing the first and second information to determine the authenticity or not of the article.
In a further aspect of the invention, a coded pattern of bars, or a bar code, is overprinted on the diffraction grating strip, with one of said coded pattern and the pattern of diffraction grating elements precessing with respect to the other and the coded pattern is read, stored, and compared as part of said first and second information, as above.
While the identification method and means described in the above-referenced patent have proved to be generally satisfactory, a problem can sometimes arise in which the overprinting of the bar code causes some of the diffraction grating elements to be too narrow. Except for the method and means described in the foregoing patent, none of such known identification means provides a high level of protection against forgery and/or copying. Also, many such identification means do not provide a high degree of assurance that duplicate identification means will not be issued to two or more users.
Accordingly, it is a principal object of the present invention to provide identification method and means to ensure that an identification is authentic and not a forgery and to make this verification without human intervention.
It is a further object of the invention to provide such method and means that makes it extremely difficult to duplicate or forge identification means.
It is an additional object of the invention to provide such method and means that is economical.
It is another object of the invention to provide such method and means that does not require precise overprinting of a second code.
It is yet a further object of the invention to provide such method and means that does not require host computer support.
It is yet an additional object of the invention to provide such method and means that renders highly unlikely that duplicate identification means will be issued to two or more users thereof.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.
The present invention achieves the above objects, among others, by providing, in a preferred embodiment, a method of providing secure identification for an article, comprising: providing on said article a diffraction grating strip comprising a pattern of a series of diffraction grating elements, each said diffraction grating element to diffract light, from a light source, in one of at least first, second, third, and fourth selected different planes, each adjacent pair of said diffraction grating elements which diffract light in said first, second, third planes being separated by a diffraction grating element which diffracts light in said fourth plane; and selectively obliterating selected ones of said diffraction grating element which diffract light in said fourth plane, such as to form a binary number consisting of obliterated and non-obliterated ones of said diffraction grating elements which diffract light in said fourth plane.